1
|
Li H, Qian J, Wang Y, Wang J, Mi X, Qu L, Song N, Xie J. Potential convergence of olfactory dysfunction in Parkinson's disease and COVID-19: The role of neuroinflammation. Ageing Res Rev 2024; 97:102288. [PMID: 38580172 DOI: 10.1016/j.arr.2024.102288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/28/2024] [Accepted: 03/30/2024] [Indexed: 04/07/2024]
Abstract
Parkinson's disease (PD) is a prevalent neurodegenerative disorder that affects 7-10 million individuals worldwide. A common early symptom of PD is olfactory dysfunction (OD), and more than 90% of PD patients suffer from OD. Recent studies have highlighted a high incidence of OD in patients with SARS-CoV-2 infection. This review investigates the potential convergence of OD in PD and COVID-19, particularly focusing on the mechanisms by which neuroinflammation contributes to OD and neurological events. Starting from our fundamental understanding of the olfactory bulb, we summarize the clinical features of OD and pathological features of the olfactory bulb from clinical cases and autopsy reports in PD patients. We then examine SARS-CoV-2-induced olfactory bulb neuropathology and OD and emphasize the SARS-CoV-2-induced neuroinflammatory cascades potentially leading to PD manifestations. By activating microglia and astrocytes, as well as facilitating the aggregation of α-synuclein, SARS-CoV-2 could contribute to the onset or exacerbation of PD. We also discuss the possible contributions of NF-κB, the NLRP3 inflammasome, and the JAK/STAT, p38 MAPK, TLR4, IL-6/JAK2/STAT3 and cGAS-STING signaling pathways. Although olfactory dysfunction in patients with COVID-19 may be reversible, it is challenging to restore OD in patients with PD. With the emergence of new SARS-CoV-2 variants and the recurrence of infections, we call for continued attention to the intersection between PD and SARS-CoV-2 infection, especially from the perspective of OD.
Collapse
Affiliation(s)
- Hui Li
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Junliang Qian
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Youcui Wang
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Juan Wang
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Xiaoqing Mi
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Le Qu
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China
| | - Ning Song
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China.
| | - Junxia Xie
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, China.
| |
Collapse
|
2
|
Wai CH, Jin J, Cyrklaff M, Genoud C, Funaya C, Sattler J, Maceski A, Meier S, Heiland S, Lanzer M, Frischknecht F, Kuhle J, Bendszus M, Hoffmann A. Neurofilament light chain plasma levels are associated with area of brain damage in experimental cerebral malaria. Sci Rep 2022; 12:10726. [PMID: 35750882 PMCID: PMC9232608 DOI: 10.1038/s41598-022-14291-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 06/03/2022] [Indexed: 11/23/2022] Open
Abstract
Neurofilament light chain (NfL), released during central nervous injury, has evolved as a powerful serum marker of disease severity in many neurological disorders, including infectious diseases. So far NfL has not been assessed in cerebral malaria in human or its rodent model experimental cerebral malaria (ECM), a disease that can lead to fatal brain edema or reversible brain edema. In this study we assessed if NfL serum levels can also grade disease severity in an ECM mouse model with reversible (n = 11) and irreversible edema (n = 10). Blood–brain-barrier disruption and brain volume were determined by magnetic resonance imaging. Neurofilament density volume as well as structural integrity were examined by electron microscopy in regions of most severe brain damage (olfactory bulb (OB), cortex and brainstem). NfL plasma levels in mice with irreversible edema (317.0 ± 45.01 pg/ml) or reversible edema (528.3 ± 125.4 pg/ml) were significantly increased compared to controls (103.4 ± 25.78 pg/ml) by three to five fold, but did not differ significantly in mice with reversible or irreversible edema. In both reversible and irreversible edema, the brain region most affected was the OB with highest level of blood–brain-barrier disruption and most pronounced decrease in neurofilament density volume, which correlated with NfL plasma levels (r = − 0.68, p = 0.045). In cortical and brainstem regions neurofilament density was only decreased in mice with irreversible edema and strongest in the brainstem. In reversible edema NfL plasma levels, MRI findings and neurofilament volume density normalized at 3 months’ follow-up. In conclusion, NfL plasma levels are elevated during ECM confirming brain damage. However, NfL plasma levels fail short on reliably indicating on the final outcomes in the acute disease stage that could be either fatal or reversible. Increased levels of plasma NfL during the acute disease stage are thus likely driven by the anatomical location of brain damage, the olfactory bulb, a region that serves as cerebral draining pathway into the nasal lymphatics.
Collapse
Affiliation(s)
- Chi Ho Wai
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany.,Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Jessica Jin
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany.,Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Marek Cyrklaff
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Christel Genoud
- Electron Microscopy Facility, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Charlotta Funaya
- Electron Microscopy Core Facility, Heidelberg University, Heidelberg, Germany
| | - Julia Sattler
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Aleksandra Maceski
- Neurologic Clinic and Policlinic, MS Center and Research Center for Clinical Neuroimmunology and Neuroscience Basel (RC2NB), University Hospital Basel, University of Basel, Basel, Switzerland
| | - Stephanie Meier
- Neurologic Clinic and Policlinic, MS Center and Research Center for Clinical Neuroimmunology and Neuroscience Basel (RC2NB), University Hospital Basel, University of Basel, Basel, Switzerland
| | - Sabine Heiland
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Michael Lanzer
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany
| | - Friedrich Frischknecht
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg, Germany.,German Center for Infection Research (DZIF), Heidelberg, Germany
| | - Jens Kuhle
- Neurologic Clinic and Policlinic, MS Center and Research Center for Clinical Neuroimmunology and Neuroscience Basel (RC2NB), University Hospital Basel, University of Basel, Basel, Switzerland
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Angelika Hoffmann
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany. .,Department of Neuroradiology, University Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Inselspital, University of Bern, Freiburgstrasse, 3010, Bern, Switzerland.
| |
Collapse
|
3
|
Koyama S, Heinbockel T. Chemical Constituents of Essential Oils Used in Olfactory Training: Focus on COVID-19 Induced Olfactory Dysfunction. Front Pharmacol 2022; 13:835886. [PMID: 35721200 PMCID: PMC9201274 DOI: 10.3389/fphar.2022.835886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
The recent increase in the number of patients with post-viral olfactory dysfunction (PVOD) following the outbreak of COVID-19 has raised the general interest in and concern about olfactory dysfunction. At present, no clear method of treatment for PVOD has been established. Currently the most well-known method to improve the symptoms of olfactory dysfunction is "olfactory training" using essential oils. The essential oils used in olfactory training typically include rose, lemon, clove, and eucalyptus, which were selected based on the odor prism hypothesis proposed by Hans Henning in 1916. He classified odors based on six primary categories or dimensions and suggested that any olfactory stimulus fits into his smell prism, a three-dimensional space. The term "olfactory training" has been used based on the concept of training olfactory sensory neurons to relearn and distinguish olfactory stimuli. However, other mechanisms might contribute to how olfactory training can improve the recovery of the olfactory sense. Possibly, the essential oils contain chemical constituents with bioactive properties that facilitate the recovery of the olfactory sense by suppressing inflammation and enhancing regeneration. In this review, we summarize the chemical constituents of the essential oils of rose, lemon, clove, and eucalyptus and raise the possibility that the chemical constituents with bioactive properties are involved in improving the symptoms of olfactory dysfunction. We also propose that other essential oils that contain chemical constituents with anti-inflammatory effects and have binding affinity with SARS-CoV-2 can be new candidates to test their efficiencies in facilitating the recovery.
Collapse
Affiliation(s)
- Sachiko Koyama
- Department of Chemistry, College of Arts and Sciences, Indiana University, Bloomington, IN, United States
| | - Thomas Heinbockel
- Department of Anatomy, College of Medicine, Howard University, Washington, DC, United States
| |
Collapse
|
4
|
Olfactory Evaluation in Alzheimer’s Disease Model Mice. Brain Sci 2022; 12:brainsci12050607. [PMID: 35624994 PMCID: PMC9139301 DOI: 10.3390/brainsci12050607] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/26/2022] [Accepted: 05/03/2022] [Indexed: 11/17/2022] Open
Abstract
Olfactory dysfunction is considered a pre-cognitive biomarker of Alzheimer’s disease (AD). Because the olfactory system is highly conserved across species, mouse models corresponding to various AD etiologies have been bred and used in numerous studies on olfactory disorders. The olfactory behavior test is a method required for early olfactory dysfunction detection in AD model mice. Here, we review the olfactory evaluation of AD model mice, focusing on traditional olfactory detection methods, olfactory behavior involving the olfactory cortex, and the results of olfactory behavior in AD model mice, aiming to provide some inspiration for further development of olfactory detection methods in AD model mice.
Collapse
|
5
|
Effect of Sensory Deprivation of Nasal Respiratory on Behavior of C57BL/6J Mice. Brain Sci 2021; 11:brainsci11121626. [PMID: 34942927 PMCID: PMC8699203 DOI: 10.3390/brainsci11121626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 11/17/2022] Open
Abstract
Nasal breathing is a dynamic cortical organizer involved in various behaviors and states, such as locomotion, exploration, memory, emotion, introspection. However, the effect of sensory deprivation of nasal respiratory breath (NRD) on behavior remain poorly understood. Herein, general locomotor activity, emotion, learning and memory, social interaction, and mechanical pain were evaluated using a zinc sulfate nasal irrigation induced nasal respiratory sensory deprivation animal model (ZnSO4-induced mouse model). In the open field test, the elevated O-maze test, and forced swim test, NRD mice exhibited depressive and anxiety-like behaviors. In memory-associated tests, NRD mice showed cognitive impairments in the hippocampal-dependent memory (Y maze, object recognition task, and contextual fear conditioning (CFC)) and amygdala-dependent memory (the tone-cued fear conditioning test (TFC)). Surprisingly, NRD mice did not display deficits in the acquisition of conditional fear in both CFC and TFC tests. Still, they showed significant memory retrieval impairment in TFC and enhanced memory retrieval in CFC. At the same time, in the social novelty test using a three-chamber setting, NRD mice showed impaired social and social novelty behavior. Lastly, in the von Frey filaments test, we found that the pain sensitivity of NRD mice was reduced. In conclusion, this NRD mouse model showed a variety of behavioral phenotypic changes, which could offer an important insight into the behavioral impacts of patients with anosmia or those with an impaired olfactory bulb (OB) (e.g., in COVID-19, Alzheimer’s disease, Parkinson’s disease, etc.).
Collapse
|
6
|
Yan Y, Aierken A, Wang C, Song D, Ni J, Wang Z, Quan Z, Qing H. A potential biomarker of preclinical Alzheimer's disease: The olfactory dysfunction and its pathogenesis-based neural circuitry impairments. Neurosci Biobehav Rev 2021; 132:857-869. [PMID: 34810025 DOI: 10.1016/j.neubiorev.2021.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/26/2021] [Accepted: 11/07/2021] [Indexed: 01/24/2023]
Abstract
The olfactory dysfunction can signal and act as a potential biomarker of preclinical AD. However, the precise regulatory mechanism of olfactory function on the neural pathogenesis of AD is still unclear. The impairment of neural networks in olfaction system has been shown to be tightly associated with AD. As key brain regions of the olfactory system, the olfactory bulb (OB) and the piriform cortex (PCx) have a profound influence on the olfactory function. Therefore, this review will explore the mechanism of olfactory dysfunction in preclinical AD in the perspective of abnormal neural networks in the OB and PCx and their associated brain regions, especially from two aspects of aberrant oscillations and synaptic plasticity damages, which help better understand the underlying mechanism of olfactory neural network damages related to AD.
Collapse
Affiliation(s)
- Yan Yan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Chunjian Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Da Song
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhe Wang
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zhenzhen Quan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| |
Collapse
|
7
|
Chen Z, Chang F, Yao L, Yuan F, Hong J, Wu D, Wei Y. Clinical significance of the cognition-related pathogenic proteins in plasma neuronal-derived exosomes among normal cognitive adults over 45 years old with olfactory dysfunction. Eur Arch Otorhinolaryngol 2021; 279:3467-3476. [PMID: 34693486 DOI: 10.1007/s00405-021-07143-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/15/2021] [Indexed: 01/25/2023]
Abstract
OBJECTIVES Exosomal Phospho-Tau-181(P-T181-tau), Total tau (T-tau), and amyloid-β peptide 42 (Aβ42) have been proved the capacity for the amnestic mild cognitive impairment (MCI) and the diagnosis of Alzheimer's disease (AD). This study aimed to explore the cognitive function and the levels of P-T181-tau, T-tau, and Aβ42 in neuronal-derived exosomes (NDEs) extracted from plasma in normal cognitive adults over 45 years old with olfactory dysfunction. METHODS A cross-sectional survey of 29 participants aged over 45 was conducted. Plasma exosomes were isolated, precipitated, and enriched by immuno-absorption with anti- L1 cell adhesion molecule (L1CAM) antibody. NDEs were characterized by CD81, and extracted NDE protein (P-T181-tau, T-tau, and Aβ42) biomarkers were quantified by enzyme-linked immunosorbent assay (ELISAs). Olfactory performance was assessed by Sniffin' Sticks and cognitive performance was assessed by Montreal Cognitive Assessment (MoCA). RESULTS There was no significant difference between adults with olfactory dysfunction and without olfactory dysfunction regarding the cognitive function as measured by MoCA and all the participants showed normal cognition. Adults with olfactory dysfunction showed a higher concentration of P-T181-tau in plasma NDEs than did adults without olfactory dysfunction (P = 0.034). Both the levels of P-T181-tau (r = - 0.553, P = 0.003) and T-tau (r = - 0.417, P = 0.034) negatively correlated with the odor identification scores. In addition, the level of T-tau negatively correlated with MoCA scores (r = - 0.597, P = 0.002). The levels of P-T181-tau (r = - 0.464, P = 0.022) and T-tau (r = - 0.438, P = 0.032) negatively correlated with the delayed recall scores. CONCLUSIONS This study demonstrated that cognition-related pathogenic proteins including P-T181-tau in plasma NDEs were significantly increased in adults over 45 years old with olfactory dysfunction before the occurrence of cognitive impairment. The impaired odor identification and the delayed recall function were highly associated with the increased levels of P-T181-tau and T-tau in plasma NDEs.
Collapse
Affiliation(s)
- Zirong Chen
- Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing, China
| | - FeiFan Chang
- Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing, China
| | - Linyin Yao
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, YaBao Road 2, Beijing, 100029, Chaoyang District, China
| | - Fan Yuan
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, YaBao Road 2, Beijing, 100029, Chaoyang District, China
| | - Junsheng Hong
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, YaBao Road 2, Beijing, 100029, Chaoyang District, China
| | - Dawei Wu
- Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, YaBao Road 2, Beijing, 100029, Chaoyang District, China.
| | - Yongxiang Wei
- Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing, China. .,Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, YaBao Road 2, Beijing, 100029, Chaoyang District, China. .,Department of Otolaryngology, Capital Institute of Pediatrics, Beijing, China.
| |
Collapse
|
8
|
Berry JK, Cox D. Increased oscillatory power in a computational model of the olfactory bulb due to synaptic degeneration. Phys Rev E 2021; 104:024405. [PMID: 34525666 DOI: 10.1103/physreve.104.024405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 06/30/2021] [Indexed: 11/07/2022]
Abstract
Several neurodegenerative diseases impact the olfactory system, and in particular the olfactory bulb, early in disease progression. One mechanism by which damage occurs is via synaptic dysfunction. Here, we implement a computational model of the olfactory bulb and investigate the effect of weakened connection weights on network oscillatory behavior. Olfactory bulb network activity can be modeled by a system of equations that describes a set of coupled nonlinear oscillators. In this modeling framework, we propagate damage to synaptic weights using several strategies, varying from localized to global. Damage propagated in a dispersed or spreading manner leads to greater oscillatory power at moderate levels of damage. This increase arises from a higher average level of mitral cell activity due to a shift in the balance between excitation and inhibition. That this shift leads to greater oscillations depends critically on the nonlinearity of the activation function. Linearized analysis of the network dynamics predicts when this shift leads to loss of oscillatory activity. We thus demonstrate one potential mechanism involved in the increased gamma oscillations seen in some animal models of Alzheimer's disease, and we highlight the potential that pathological olfactory bulb behavior presents as an early biomarker of disease.
Collapse
Affiliation(s)
- J Kendall Berry
- University of California, Davis, Davis, California 95616, USA
| | - Daniel Cox
- University of California, Davis, Davis, California 95616, USA
| |
Collapse
|
9
|
Dan X, Wechter N, Gray S, Mohanty JG, Croteau DL, Bohr VA. Olfactory dysfunction in aging and neurodegenerative diseases. Ageing Res Rev 2021; 70:101416. [PMID: 34325072 PMCID: PMC8373788 DOI: 10.1016/j.arr.2021.101416] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/15/2022]
Abstract
Alterations in olfactory functions are proposed to be early biomarkers for neurodegeneration. Many neurodegenerative diseases are age-related, including two of the most common, Parkinson's disease (PD) and Alzheimer's disease (AD). The establishment of biomarkers that promote early risk identification is critical for the implementation of early treatment to postpone or avert pathological development. Olfactory dysfunction (OD) is seen in 90% of early-stage PD patients and 85% of patients with early-stage AD, which makes it an attractive biomarker for early diagnosis of these diseases. Here, we systematically review widely applied smelling tests available for humans as well as olfaction assessments performed in some animal models and the relationships between OD and normal aging, PD, AD, and other conditions. The utility of OD as a biomarker for neurodegenerative disease diagnosis and future research directions are also discussed.
Collapse
Affiliation(s)
- Xiuli Dan
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Noah Wechter
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Samuel Gray
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Joy G Mohanty
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Section on DNA Repair, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; Danish Center for Healthy Aging, University of Copenhagen, 2200 Copenhagen, Denmark.
| |
Collapse
|
10
|
The Olfactory System as Marker of Neurodegeneration in Aging, Neurological and Neuropsychiatric Disorders. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18136976. [PMID: 34209997 PMCID: PMC8297221 DOI: 10.3390/ijerph18136976] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/19/2021] [Accepted: 06/24/2021] [Indexed: 12/14/2022]
Abstract
Research studies that focus on understanding the onset of neurodegenerative pathology and therapeutic interventions to inhibit its causative factors, have shown a crucial role of olfactory bulb neurons as they transmit and propagate nerve impulses to higher cortical and limbic structures. In rodent models, removal of the olfactory bulb results in pathology of the frontal cortex that shows striking similarity with frontal cortex features of patients diagnosed with neurodegenerative disorders. Widely different approaches involving behavioral symptom analysis, histopathological and molecular alterations, genetic and environmental influences, along with age-related alterations in cellular pathways, indicate a strong correlation of olfactory dysfunction and neurodegeneration. Indeed, declining olfactory acuity and olfactory deficits emerge either as the very first symptoms or as prodromal symptoms of progressing neurodegeneration of classical conditions. Olfactory dysfunction has been associated with most neurodegenerative, neuropsychiatric, and communication disorders. Evidence revealing the dual molecular function of the olfactory receptor neurons at dendritic and axonal ends indicates the significance of olfactory processing pathways that come under environmental pressure right from the onset. Here, we review findings that olfactory bulb neuronal processing serves as a marker of neuropsychiatric and neurodegenerative disorders.
Collapse
|
11
|
Tzeng WY, Figarella K, Garaschuk O. Olfactory impairment in men and mice related to aging and amyloid-induced pathology. Pflugers Arch 2021; 473:805-821. [PMID: 33608800 PMCID: PMC7895745 DOI: 10.1007/s00424-021-02527-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/07/2021] [Accepted: 01/28/2021] [Indexed: 12/31/2022]
Abstract
Olfaction, or the sense of smell, is one of the most ancient senses in men and mice, important for a large variety of innate and acquired behaviors. Clinical data reveal an early impairment of olfaction during normal aging and in the course of neurodegenerative diseases, but the underlying cellular/molecular mechanisms remain obscure. In the current review, we compare different aspects of the aging- and Alzheimer's disease related impairment of olfaction in men and mice, aiming at the identification of common morbidities and biomarkers, which can be analyzed in detail in the appropriate mouse models. We also identify common, often interdependent (patho)physiological pathways, including but not limited to extracellular amyloid depositions, neuroinflammation, ɛ4 allele of the apolipoprotein E, CNS insulin resistance, and the impairment of adult neurogenesis, to be targeted by basic and clinical research.
Collapse
Affiliation(s)
- Wen-Yu Tzeng
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Katherine Figarella
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany
| | - Olga Garaschuk
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Keplerstr. 15, 72074, Tübingen, Germany.
| |
Collapse
|
12
|
Heinbockel T, Bhatia-Dey N, Shields VDC. Endocannabinoid-mediated neuromodulation in the main olfactory bulb at the interface of environmental stimuli and central neural processing. Eur J Neurosci 2021; 55:1002-1014. [PMID: 33724578 DOI: 10.1111/ejn.15186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 02/10/2021] [Accepted: 03/05/2021] [Indexed: 12/16/2022]
Abstract
The olfactory system has become an important functional gateway to understand and analyze neuromodulation since olfactory dysfunction and deficits have emerged as prodromal and, at other times, as first symptoms of many of neurodegenerative, neuropsychiatric and communication disorders. Considering olfactory dysfunction as outcome of altered, damaged and/or inefficient olfactory processing, in the current review, we analyze how olfactory processing interacts with the endocannabinoid signaling system. In the human body, endocannabinoid synthesis is a natural and on-demand response to a wide range of physiological and environmental stimuli. Our current understanding of the response dynamics of the endocannabinoid system is based in large part on research advances in limbic system areas, such as the hippocampus and the amygdala. Functional interactions of this signaling system with olfactory processing and associated pathways are just emerging but appear to grow rapidly with multidimensional approaches. Recent work analyzing the crystal structure of endocannabinoid receptors bound to their agonists in a signaling complex has opened avenues for developing specific therapeutic drugs that could help with neuroinflammation, neurodegeneration, and alleviation/reduction of pain. We discuss the role of endocannabinoids as signaling molecules in the olfactory system and the relevance of the endocannabinoid system for synaptic plasticity.
Collapse
Affiliation(s)
- Thomas Heinbockel
- Department of Anatomy, Howard University College of Medicine, Washington, DC, USA
| | - Naina Bhatia-Dey
- Department of Anatomy, Howard University College of Medicine, Washington, DC, USA
| | - Vonnie D C Shields
- Biological Sciences Department, Fisher College of Science and Mathematics, Towson University, Towson, MD, USA
| |
Collapse
|
13
|
Functional Alterations in the Olfactory Neuronal Circuit Occur before Hippocampal Plasticity Deficits in the P301S Mouse Model of Tauopathy: Implications for Early Diagnosis and Translational Research in Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21155431. [PMID: 32751531 PMCID: PMC7432464 DOI: 10.3390/ijms21155431] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/18/2020] [Accepted: 07/24/2020] [Indexed: 02/06/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by neuronal loss and impaired synaptic transmission, ultimately leading to cognitive deficits. Early in the disease, the olfactory track seems most sensitive to tauopathy, while most plasticity studies focused on the hippocampal circuits. Functional network connectivity (FC) and long-term potentiation (LTP), considered as the plasticity substrate of learning and memory, were longitudinally assessed in mice of the P301S model of tauopathy following the course (time and location) of progressively neurodegenerative pathology (i.e., at 3, 6, and 9 months of age) and in their wild type (WT) littermates. Using in vivo local field potential (LFP) recordings, early (at three months) dampening in the gamma oscillatory activity and impairments in the phase-amplitude theta-gamma coupling (PAC) were found in the olfactory bulb (OB) circuit of P301S mice, which were maintained through the whole course of pathology development. In contrast, LFP oscillatory activity and PAC indices were normal in the entorhinal cortex, hippocampal CA1 and CA3 nuclei. Field excitatory postsynaptic potential (fEPSP) recordings from the Shaffer collateral (SC)-CA1 hippocampal stratum pyramidal revealed a significant altered synaptic LTP response to high-frequency stimulation (HFS): at three months of age, no significant difference between genotypes was found in basal synaptic activity, while signs of a deficit in short term plasticity were revealed by alterations in the fEPSPs. At six months of age, a slight deviance was found in basal synaptic activity and significant differences were observed in the LTP response. The alterations in network oscillations at the OB level and impairments in the functioning of the SC-CA1 pyramidal synapses strongly suggest that the progression of tau pathology elicited a brain area, activity-dependent disturbance in functional synaptic transmission. These findings point to early major alterations of neuronal activity in the OB circuit prior to the disturbance of hippocampal synaptic plasticity, possibly involving tauopathy in the anomalous FC. Further research should determine whether those early deficits in the OB network oscillations and FC are possible mechanisms that potentially promote the emergence of hippocampal synaptic impairments during the progression of tauopathy.
Collapse
|
14
|
Endocannabinoid-Mediated Neuromodulation in the Olfactory Bulb: Functional and Therapeutic Significance. Int J Mol Sci 2020; 21:ijms21082850. [PMID: 32325875 PMCID: PMC7216281 DOI: 10.3390/ijms21082850] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
Endocannabinoid synthesis in the human body is naturally occurring and on-demand. It occurs in response to physiological and environmental stimuli, such as stress, anxiety, hunger, other factors negatively disrupting homeostasis, as well as the therapeutic use of the phytocannabinoid cannabidiol and recreational use of exogenous cannabis, which can lead to cannabis use disorder. Together with their specific receptors CB1R and CB2R, endocannabinoids are major components of endocannabinoid-mediated neuromodulation in a rapid and sustained manner. Extensive research on endocannabinoid function and expression includes studies in limbic system structures such as the hippocampus and amygdala. The wide distribution of endocannabinoids, their on-demand synthesis at widely different sites, their co-existence in specific regions of the body, their quantitative differences in tissue type, and different pathological conditions indicate their diverse biological functions that utilize specific and overlapping pathways in multiple organ systems. Here, we review emerging evidence of these pathways with a special emphasis on the role of endocannabinoids in decelerating neurodegenerative pathology through neural networks initiated by cells in the main olfactory bulb.
Collapse
|